I am 26 years old and just finished my period a few days ago. The last two nights my left nipple has felt some strange kind of pain. It's only in the left, and it's only the nipple itself, nowhere in the areola or beyond. It happens only in my sleep and feels like it is being squeezed or slightly twisted. The pain seeped into a dream I was having two nights ago, and I woke up with the pain going away, but still having a sensation like it had just been somewhat roughly manipulated. Last night I felt it, though I didn't rightly dream anything about it, and I woke up with a duller but similar sensation. It has not ever occurred during the day. Is there a chance I've just been sleeping on my breast strangely, or could there be any other causes? Thank you in advance, and I'm willing to offer up further information if necessary.